All Problems

Interference of Light

Problem 5.89

A plano-convex glass lens with curvature radius of spherical surface R=12.5 cmR=12.5 \mathrm{~cm} is pressed against a glass plate. The diameters of the tenth and fifteenth dark Newton's rings in reflected light are equal to d1=1.00 mmd_{1}=1.00 \mathrm{~mm} and d2=1.50 mm.d_{2}=1.50 \mathrm{~mm} . Find the wavelength of light.

Reveal Answer
λ=1/4(d22−d12)/R(k2−k1)=0.50μm, where k1 and k2are the number of the dark rings\lambda=1 / 4\left(d_{2}^{2}-d_{1}^{2}\right) / R\left(k_{2}-k_{1}\right)=0.50 \mu \mathrm{m}, \text { where } k_{1} \text { and } k_{2} \text {are the number of the dark rings}
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